Over the weekend I finished the audio version of Jill Lepore’s monumental survey of American history, “These Truths,” published in 2018. At 960 pages or, in my case, 29 hours, the book is a major commitment, but it’s well worth it. That said, one thing I learned was that I already knew a lot about American history, so much of “These Truths” was familiar to me. The first is Lepore’s assertion that fears that the British would abolish slavery was one of the driving forces behind the American Revolution. Lord Dunmore, the royal governor of Virginia, intended to offer freedom to slaves who would join the British army.